The present invention relates to a golf club head having a face backside thereof reinforced with ribs.
Recently, the golf club heads are becoming larger in size but smaller in thickness, so that a face portion tends to suffer insufficient strength. A method of affixing the ribs to the face backside has been known as a measure for meeting the purposes of reducing the thickness of the face and increasing the strength thereof.
Japanese Unexamined Patent Publication No. 2003-290396 (Claim 1, Claim 2, FIG. 1, FIG. 2) discloses a golf club head wherein a plurality of ribs are provided as extended vertically, wherein the ribs located closer to a toe-side and a heel-side are accordingly decreased in height and wherein the individual ribs have a constant height distribution with respect to a longitudinal direction thereof or heights progressively increased toward a bottom side (sole side).
In spite of a great rib volume (rib weight), the above prior-art golf club head fails to achieve a sufficient face-strength reinforcing effect (hereinafter, referred to as “face reinforcement effect” or simply as “reinforcement effect”). Since all the ribs are extended in the vertical direction, the face is excessively increased in rigidity particularly at its toe-side and heel-side because of the ribs extended in the vertical direction. As a result, face vibration is excessively limited at impact with a ball.